Voltage mode voltage regulator with current mode start-up
AssigneeSemiconductor Components Industries, LLC
InventorsLoic Cunnac, Paolo Migliavacca, Philippe Goyhenetche, Michael J. Gay
Life of this patent
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Abstract
A voltage regulator (15) utilizes a first current source (31) and a second current source (32) to form a reference current to limit current flow through an output transistor (13) during a start-up period. After the start-up period expires, the first current source (31) is disabled and the voltage regulator (15) controls the output voltage produced by the output transistor (13) instead of controlling the current flow through the output transistor (13).
Claims16
A method of forming a voltage regulator comprising:
- forming the voltage regulator to limit a current flow through an output transistor to a first value during a start-up period and to control an output voltage value formed by the output transistor instead of the current flow after the start-up period including forming the voltage regulator to enable a first current source and a second current source to generate a first reference current during the start-up period and to disable the second current source after the start-up period to form a second reference current that is greater than the first reference current.
A method of forming a voltage regulator comprising:
- forming a current limit circuit to enable both a first current source and a second current source to provide a first reference current to set a drive voltage of an output transistor during a start-up period;
- and
- forming the current limit circuit to disable the first reference current after the start-up period.
A voltage regulator comprising:
- an output transistor having a first current carrying electrode coupled to a voltage source, a second current carrying electrode coupled to an output of the voltage regulator, and a control electrode;
- a sense transistor having a first current carrying electrode coupled to the voltage source, a control electrode coupled to the control electrode of the output transistor, and a second current carrying electrode;
- a reference transistor having a first current carrying electrode coupled to the second current carrying electrode of the sense transistor, a control electrode coupled to the first current carrying electrode, and a second current carrying electrode coupled to a power return;
- a first current source transistor having a first electrode coupled to the first current carrying electrode of the reference transistor, and a second electrode coupled to the second current carrying electrode of the reference transistor;
- and
- a second current source transistor having a first current carrying electrode coupled to the voltage source, and a second current carrying electrode coupled to the first current carrying electrode of the reference transistor through a switch transistor.
Dependencies are inferred from the claim text.